Groveller, cenum, and allow-undeclared-values
#405
Replies: 3 comments 3 replies
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Just to be clear, given the following C code: I would like the ability to achieve what the following |
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You can see here the code that parses `cenum` grovel directive and emits
the corresponding C code that in turn emits the defcenum form.
https://github.com/cffi/cffi/blob/master/grovel%2Fgrovel.lisp#L573
Let me know if you need help figuring the details out.
…On Mon, 3 Feb 2025, 21:20 Andrew Walter, ***@***.***> wrote:
Just to be clear, given the following C code:
typedef enum {
FOO_BAR,
FOO_BAZ,
FOO_QUX
} Foo;
Foo make_a_foo(int x) {
switch(x) {
case 0: return FOO_BAR;
case 1: return FOO_BAZ;
default: return FOO_QUX;
}
}
I would like the ability to achieve what the following defcenum does, but
using cenum and the Groveller instead.
(cffi:defcenum (Foo :int :allow-undeclared-values t)
(:bar 0)
(:baz 1))
(cffi:defcfun "make_a_foo" Foo
(x :int))
(make-a-foo 3) ;; => 2
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After playing around trying to implement - I think the biggest issue is that the syntax of I might just disallow providing |
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@mister-walter If I understand correctly, you're trying to map any unkown value to a specific enum member. You can achieve that with a custom translator. I'm not convinced this should be part of the core CFFI. |
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I'm happy to have the unknown value remain untranslated (insofar as it remains an integer rather than getting turned into a symbol) - the behavior of In my case I really just want CFFI to "keep calm and carry on" when a C function ends up returning an unknown enum member. If you're saying I can just override the foreign->lisp translator generated by |
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Just to clarify: my issue here is that even though |
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I'm using the Groveller to create bindings for some C enums. The C library I'm binding to may add additional enum values.
I would like to pass
:allow-undeclared-values tto the underlyingdefcenumcall thatcenumwill end up expanding out into, so that if the library produces one of the new values (that doesn't appear in thecenumcall) the function that translates foreign values to Lisp values does not error out and simply returns the numeric value returned by the C function.What is the easiest way to do this? Do I need to write some custom Grovel syntax and arrange for it to be loaded prior to the running of the Groveller, or can I set the
allow-undeclared-valuesfield of the underlyingforeign-enuminstance after the fact?Happy to create a PR to update
cenumso it allows the:allow-undeclared-valueskeyword argument to be passed thru todefcenum.Beta Was this translation helpful? Give feedback.
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